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December 8, 2005

Atmospheric Ozone Drop May Lead to More Cataracts

by Sam Savage

NEW YORK -- An increase in exposure to ultraviolet radiation as result of ozone depletion in the stratosphere could in future lead to a considerable increase in the incidence of cataracts in the US population, researchers report.

Ozone screens out most of the ultraviolet radiation coming from the sun. Although progress is being made in reducing the degree of ozone depletion, Dr. Sheila K. West of Johns Hopkins Hospital, Baltimore and colleagues note in the American Journal of Epidemiology that cataracts are still a health effect of particular concern.

They also note that unlike skin cancer, which is much more prevalent in those with light skin, cataracts affect African Americans at higher rate than Caucasians.

The researchers obtained data from a Maryland population-based study, involving more than 2500 subjects, which provided information on cataract and ultraviolet radiation exposure. With this and other data the team was able to create a model of cataract risk in the US population related to increasing ultraviolet radiation arising from falling ozone levels of 5 to 20 percent.

Based on this analysis, the researchers estimated that by 2050 cataract rates would increase by 1.3 percent to 6.9 percent. This could amount to as many as 830,0000 extra cases by 2050 and could result in an extra expenditure of close to $3 billion, calculated using 2003 costs for cataract operations.

The team notes that ozone-depleting substances continue to degrade the stratosphere, and although there is a geographic variability in ultraviolet exposure, they stress "the importance of vigilance in adopting sun avoidance behaviors."